Large material conveyer systems are in widespread use in various industries for moving materials from one location to another. For example, conveyer systems are used to move sand, gravel, crushed ore or rock, coal, and other materials, depending upon the particular industry involved.
Material conveyers typically include a very long endless belt which is supported on rollers carried by a large elongated frame. Large forces are involved due to the great weight of the material being conveyed and the speed at which the belt is driven. The rollers (e.g., idler pulleys) normally have a cylindrical metal body which is rotatably supported at each end by a bearing. A shaft extends outwardly from each end of the roller or pulley and is connected to the bearing.
After a period of use, one or both of the bearings in an idler pulley will fail. This can result in lack of rotational freedom of the pulley (i.e., it fails to rotate when the conveyer belt moves over it). As a result, the conveyer belt can cause extraordinary wear of the cylindrical body of the pulley. Even if the bearings do not fail, the conveyer belt will also cause wear of the cylindrical body of the pulley.
When the pulley becomes unduly worn, whether because a bearing fails or because of lengthy use of a conveyer, it is necessary to either replace the entire pulley or repair it. Replacement of the entire pulley is expensive.
A previously proposed method for repairing a heavily worn pulley involves placing a rubber sleeve over it to provide a new wearing surface. This technique has a number of disadvantages associated with it, however.
For example, the sleeve must have an internal diameter slightly smaller than the diameter of the pulley to be repaired. Then the sleeve must be driven onto the pulley from one end. Of course, the pulley must be first removed from the conveyer before it can be repaired with such technique. The sleeve may even have to be heated in order to obtain sufficient pliability to enable it to be placed over the pulley.
Also, because idler pulleys of many different diameters and lengths are in conventional use, it would be necessary to manufacture and stock numerous different sizes of sleeves if they are to be used as repair items. Furthermore, the surface of idler pulleys wear unevenly. As a result, the diameter of the pulley can vary along its length when it becomes worn. This compounds the problem of obtaining proper fit of an off-the-shelf sleeve on a worn pulley in the field.
There has not heretofore been provided an effective and inexpensive technique for repair of worn idler pulleys of various diameters and lengths.